Thailand Unlimited 30 days
AIS / True Move H / NT
- Data
- Unlimited (FUP)
- Validity
- 30 days
- Hotspot
- Yes
- Technology
- 4G / 5G
- Unlimited
- 5G ready
- Hotspot
Validity starts on first connection at the destination
from$55.90
Sizing an eSIM for a three-week trip
Data to plan for across 21 days at three levels of use, and which plan shape works out better at this trip length.
Quick answer
- For 21 days: about 22GB at normal use, 10GB if light, 45GB if heavy.
- The numbers come from a fixed formula plus a 15 percent buffer, not from measuring your own use.
How much data 21 days needs
The figures below take three levels of daily use, multiply by the number of days, and add 15 percent for app updates and photo backup — the two things travellers forget.
| Level of use | Roughly per day | Total for 21 days |
|---|---|---|
| Light: maps, chat, email | 0.4GB | 10GB |
| Normal: social, photos, short video | 0.9GB | 22GB |
| Heavy: streaming, video calls, hotspot | 1.9GB | 45GB |
The plan shape that fits this length
At 21 days we would start with a daily plan, because that is where price per gigabyte and the risk of wasted data balance out. If your usage is uneven, weigh the top-up terms as well.
These are estimates from a fixed formula, not measurements of your own use. If you have data figures from a previous trip, trust those first.
What people forget when sizing by days
Multiplying days by daily use gets you close, but real trips are lumpy. Day one is usually the heaviest — navigating, checking in, messaging home — while a day on a tour or a long transfer can use almost nothing.
- The first and last days run above average; keep that in mind
- Travelling as a pair on one hotspot means budgeting for two people, not one
- Turning off automatic photo backup over mobile data, and syncing on Wi-Fi instead, is the single biggest saving available
FAQ
When does the 21-day clock start?+
Most plans start counting at first connection to a network at the destination, not at payment — but some count from the purchase date. Check the activation-policy line on the plan page before buying weeks ahead.
Should I buy exactly 21 days or add a buffer?+
Add at least one day. Delays, layovers and the trip home routinely spill past midnight, and a plan that expires while you are still at the airport leaves you offline exactly when you need it.
Daily or fixed data at this trip length?+
At 21 days the deciding factor is consistency. Even daily use suits a daily plan, which caps the cost predictably. Spiky use — heavy some days, nothing on others — suits a fixed-data pool.
Related
Plans that cover 21 days
Filtered to plans whose validity outlasts the trip and whose data clears the light-use estimate.
Unlimited
Hong Kong Unlimited 30 days
CSL / HKT / China Mobile Hong Kong / SmarTone
- Data
- Unlimited (FUP)
- Validity
- 30 days
- Hotspot
- Yes
- Technology
- 4G / 5G
- Unlimited
- 5G ready
- Hotspot
Validity starts on first connection at the destination
from$56.90
Vietnam Unlimited 30 days
Viettel / Vinaphone / MobiFone
- Data
- Unlimited (FUP)
- Validity
- 30 days
- Hotspot
- Yes
- Technology
- 4G / 5G
- Unlimited
- 5G ready
- Hotspot
Validity starts on first connection at the destination
from$57.90
Singapore Unlimited 30 days
Singtel / StarHub / M1
- Data
- Unlimited (FUP)
- Validity
- 30 days
- Hotspot
- Yes
- Technology
- 4G / 5G
- Unlimited
- 5G ready
- Hotspot
Validity starts on first connection at the destination
from$58.90
China Unlimited 30 days
China Mobile / China Unicom / China Telecom
- Data
- Unlimited (FUP)
- Validity
- 30 days
- Hotspot
- Yes
- Technology
- 4G / 5G
- Unlimited
- 5G ready
- Hotspot
Validity starts on first connection at the destination
from$60.90
Taiwan Unlimited 30 days
Chunghwa Telecom / Taiwan Mobile / Far EasTone
- Data
- Unlimited (FUP)
- Validity
- 30 days
- Hotspot
- Yes
- Technology
- 4G / 5G
- Unlimited
- 5G ready
- Hotspot
Validity starts on first connection at the destination
from$60.90
South Korea Unlimited 30 days
SK Telecom / KT / LG U+
- Data
- Unlimited (FUP)
- Validity
- 30 days
- Hotspot
- Yes
- Technology
- 4G / 5G
- Unlimited
- 5G ready
- Hotspot
Validity starts on first connection at the destination
from$62.90
Philippines Unlimited 30 days
Globe / Smart
- Data
- Unlimited (FUP)
- Validity
- 30 days
- Hotspot
- Yes
- Technology
- 4G / 5G
- Unlimited
- 5G ready
- Hotspot
Validity starts on first connection at the destination
from$64.90
Japan Unlimited 30 days
NTT DOCOMO / KDDI (au) / SoftBank
- Data
- Unlimited (FUP)
- Validity
- 30 days
- Hotspot
- Yes
- Technology
- 4G / 5G
- Unlimited
- 5G ready
- Hotspot
Validity starts on first connection at the destination
from$65.90